1. Technical Field
The following description relates to one or more network devices that begin to utilize a service provided by a service providing server by sending to the service providing server a certificate acquired from an authentication server on a network.
2. Related Art
So far a service providing server has been known, which provides various services in response to requests from network devices (e.g., information processing terminal devices such as personal computers). The service providing server performs an authentication process to determine whether a user of the network device is authorized to utilize a service requested, and provides the service after determining that the user is authorized.
For example, according to a known technique, an authentication server, which issues a certificate attesting that the user is authorized, is installed on a network, and the user is permitted to utilize an intended service provided by the service providing server using the certificate issued by the authentication server.
The above technique is adapted to attain a so-called single sign-on, and the Kerberos authentication is a typical example of an authentication method for the technique. In the Kerberos authentication, as exemplified in FIG. 9, when the user inputs information such as a user name and a password into a user terminal device (i.e., a network device) and logs in the user terminal device, the user terminal device transmits the information to the authentication server. Then, the user terminal device acquires from the authentication server a certificate that is referred to as a credential, and keeps holding the certificate (the credential) until the user terminates the use of the user terminal device (i.e., until a log-off operation is performed).
Further, when the user inputs a request for usage of the service providing server (an application server in FIG. 9) through the user terminal device in the log-in state, the user terminal device transmits to the application server the service usage request along with the certificate (the credential).
Then, the service providing server (the application server) determines, using the authentication server, whether the certificate (the credential) transmitted along with the service usage request is proper. When the certificate (the credential) is determined to be proper, the service providing server permits the user terminal device to utilize the requested service.